Safe and stable housing is essential to recovery from addiction to alcohol and drugs. Recovery housing represents a unique and innovative way to ensure that individuals in recovery have access to housing that facilitates it. A growing body of research supports the effectiveness of recovery housing, and findings to support recovery housing evidence-based practices are beginning to emerge. However, there are critical gaps in our understanding of recovery housing. The recovery housing literature is fragmented, focusing on certain types of recovery housing or recovery housing in specific geographic regions. We also lack tools necessary to provide a complete picture of the national recovery housing landscape. To address these gaps, the aims of this 4-year health services research proposal are to: (1) Examine availability of recovery housing in the US and characterize environments where recovery residences are located; (2) Characterize the national recovery housing landscape in terms of organizational and residence characteristics, policies, practices, programming, and service delivery orientation and explore whether these characteristics vary depending on where residences are located; (3) Identify underlying patterns among recovery residences and examine the association between these patterns and existing categorizations of treatment and recovery housing; (4) Explore organizational, residence, policy, practice, programming, and delivery orientation characteristics associated with recovery housing evidence-based practices. To address these aims, we will consult with a diverse group of experts in the treatment, recovery, housing, and recovery housing fields to create a national database of recovery residences and survey of a random sample of 800 residences stratified by state. All residences in the database will be geocoded and linked with contextual information, including data on alcohol and drug treatment availability, alcohol outlets, and crime. The survey will collect critical data on organizational and residence features, policies, practices, programming, and service delivery orientation to illustrate essential features of recovery housing and to delineate different types of it. The proposed study will constitute the largest and most diverse study of recovery housing to date, laying the groundwork for surveillance of this important component of the housing, treatment, and recovery support services landscape. It will provide much needed descriptive data on a nationally-representative sample of recovery residences, and it will facilitate large-scale national studies of recovery residences, comparative effectiveness and cost-effectiveness studies of different types of recovery residences, studies identifying type sort of recovery residence works best for whom, and studies of policies and organizational practices that increase recovery housing access and utilization.